Configuration file systems

There are several planning decisions that you need to make when setting up a WebSphere® Application Server for z/OS® configuration file system.

Cell, node, and server settings as well as deployed applications are stored in the WebSphere Application Server for z/OS configuration file system. You can use a zSeries file system (ZFS) or hierarchical file system (HFS) for the configuration file system.
Tip: Beginning with WebSphere Application Server for z/OS Version 7.0, the SBBOLOAD and SBBOLD2 datasets no longer exist. This is because the load modules are now in the product file system. If you want to switch a configuration from using load modules in the product file system to using load modules in a dataset, you can use the tool described in switchModules command. Beginning with WebSphere Application Server for z/OS Version 8.0, the server_dlls_in_hfs environment variable must also be set to 0 for the server to use the DLLs that have been put into a dataset that is in STEPLIB, LPA, or link list. In order for the daemon to pick up the DLLs, WAS_DAEMON_ONLY_server_dlls_in_hfs should be set at the cell level.

Each node needs a home directory

Every WebSphere Application Server for z/OS node--whether a standalone application server, deployment manager, managed application server node, or location service daemon--requires a read/write home directory, sometimes referred to as its WAS_HOME.

This is the structure of a WebSphere Application Server for z/OS configuration file system, mounted at /WebSphere/V8R0. It contains a WebSphere Application Server home directory for a single application server named BBOS001, with a cell and a node both named SYSA.
/WebSphere/V8R0
  /AppServer
    /bin
    /classes
    /java
    /lib
    /logs
    /profiles
      /default -> this is the profile_root directory  
    /temp
    ...
   /Daemon
    /config    
      /SYSA
   SYSA.SYSA.BBODMNB -> /WebSphere/V8R0/Daemon/config/SYSA/SYSA/BBODMNB
   SYSA.SYSA.BBOS001 ->  
/WebSphere/V8R0/AppServer/profiles/default/config/cells/SYSA/nodes/SYSA
   /servers/server1
   SYSA.SYSA.BBOS001.HOME ->  /WebSphere/V8R0/AppServer
The WebSphere Application Server home directory for BBOS001 is named AppServer. It contains directories with complete configuration information for the SYSA node and the BBOS001 server.
The /Daemon directory contains configuration information for location service daemons defined to nodes in this configuration file system.
Note: The /Daemon/config subdirectory is subdivided by cell name. If the cells have different short names, the location service daemon information for each is kept separate.
The daemon home directory has the fixed WebSphere Application Server home name Daemon.

Symbolic links are used to access startup parameters

In addition to the WebSphere Application Server home directories themselves, the configuration file system contains a multipart symbolic link for each server that points to the startup parameters for the server. The symbolic link is named cell_short_name.node_short_name.server_short_name.

The sample configuration file system above contains a symbolic link SYSA.SYSA.BBODMNB to start the location service daemon and a symbolic link SYSA.SYSA.BBOS001 to start the BBOS001 application server. The second symbolic link is specified in the ENV parameter on the START command when the server or location service daemon is started from the MVS console:

START procname,JOBNAME=BBOS001,ENV=SYSA.SYSA.BBOS001

Each symbolic link points to the subdirectory where the server's was.env file resides. This file contains the information required to start the server.

Note: During post-installation processing, described below, the server JCL needs to specify the WebSphere Application Server home directory itself, rather than the location of the was.env file. This is the purpose of the SYSA.SYSA.BBOS001.HOME symbolic link shown above.

Sharing the configuration file system between cells

Two or more WebSphere Application Server for z/OS cells (standalone application server, Network Deployment, or both) can share a WebSphere Application Server for z/OS configuration file system, provided the following conditions are met:
  • All cells using the configuration file system must be set up using the same common groups and users. In particular, each must have the same administrator user ID and configuration group.
  • The cells must have distinct cell short names.
  • Each node must have its own WAS_HOME directory that is not shared with any other node or cell.
As noted above, you can share the daemon home directory (/Daemon) between cells, as it has subdirectories farther down for each cell in the configuration file system.
Note: Be aware that sharing a configuration file system between cells increases the likelihood that problems with one cell might cause problems with other cells in the same configurations file system.

Sharing the configuration file system between systems

Two or more z/OS systems can share a configuration file system, provided the z/OS systems have a shared file system and the configuration file system is mounted R/W. All updates are made by the z/OS system that "owns" the mount point. For a Network Deployment cell, this is generally the z/OS system on which the cell deployment manager is configured.

Choosing a WebSphere Application Server for z/OS configuration file system mount point

The choice of WebSphere Application Server for z/OS configuration file system mount points depends on your z/OS system layout, the nature of the application serving environments involved, and the relative importance of several factors: ease of setup, ease of maintenance, performance, recoverability, and the need for continuous availability.

Choosing WebSphere Application Server home directory names

The WebSphere Application Server home directory is always relative to the configuration file system in which it resides. In the Profile Management Tool or the zpmt command, therefore, you choose the configuration file system mount point on one panel and fill in just the single directory name for the home directory on another. But when instructions direct you to go to the WAS_HOME directory for a server, they are referring to the entire path name, configuration file system and home directory name combined (/WebSphere/V8R0/AppServer for example).

You can choose any name you want for a home directory if it is unique in the configuration file system. If you are creating a standalone application server or new managed server node to federate into a Network Deployment cell, be sure to choose one that is not in use in the Network Deployment cell's configuration file system.

If you have one node per system, you might want to use some form of the node name or system name. Alternatively, you can use "DeploymentManager" for the deployment manager and "AppServern" for each application server node.

Relationship between the configuration file system and the product file system

The configuration file system contains a large number of symbolic links to files in the product file system (/usr/lpp/zWebSphere/V8R0 by default). This allows the server processes, administrator, and clients to access a consistent WebSphere Application Server for z/OS code base.

Note that these symbolic links are set up when the WebSphere Application Server home directory is created and are very difficult to change. Therefore, systems that require high availability should keep a separate copy of the WebSphere Application Server for z/OS product file system and product datasets for each maintenance or service level in use (test, assurance, production, and so forth) to allow system maintenance, and use intermediate symbolic links to connect each configuration file system with its product file system.

Tip: If you configure your Network Deployment environment using the default value for the product file system path in the Profile Management Tool or the zpmt command, it will result in all the nodes pointing directly at the mount point of the product file system. This makes rolling maintenance in a nondisruptive manner almost impossible. If a cell is configured in this way, applying service to the product file system affects all the nodes at the same time; and if multiple cells are configured in this way, applying service to the product file system affects all the cells at the same time. You might want to specify what is referred to as an "intermediate symbolic link" between each node's configuration file system and the actual mount point of the product file system. This strategy is described in the WebSphere Application Server for z/OS V5 - Planning for Test, Production and Maintenance white paper. See the WebSphere z/OS V6 -- WSC Sample ND Configuration white paper for more information about this issue and its relationship to applying maintenance. See the WebSphere for z/OS: Updating an Existing Configuration HFS to Use Intermediate Symbolic Links instructions for information on obtaining and using a utility that would allow you to update an existing configuration file system to use intermediate symbolic links.

When a WebSphere Application Server for z/OS node is started, the service level of the configuration is compared against the service level of the product file system. If the configuration file system service level is higher than that of the product file system (probably meaning that an old product file system is mounted), the node's servers will terminate with an error message. If the configuration file system service level is lower than that of the product file system (meaning that service has been applied to the product code base since the node was last started), a task called the post-installer checks for any actions that need to be performed on the configuration file system to keep it up to date.




Related concepts
z/OS JCL cataloged procedures
Related reference
switchModules command
Concept topic Concept topic    

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